In general, an electronic device such as a TV tuner box or a computer usually installs a port (USB port, network port, mouse port or speaker port, etc) on its main board, and a so-called electromagnetic interference (EMI) device such as a conducting plate is provided for grounding and eliminating noises to provide a good signal transmission quality without being affected by the noises.
Referring to FIGS. 1 and 2 respectively for a perspective view and an enlarged view of a traditional expansion card slot used in a computer for installing a wireless network card, a memory card or an external hard disk, the expansion card slot structure 9 includes a slot base 91, an insert slot disposed at the front end of the slot base 91, a rear-end port 912, and a shield bracket 92 installed at the rear-end port 912 for providing an electromagnetic interference (EMI) effect.
In FIGS. 1 and 2, the slot base 91 comprises a plurality of fixing pins 93, each having an upper distal edge 931 and a lower distal edge 932, wherein the lower distal edge 932 includes a latch portion 933 installed on a main board (not shown in the figure).
In a traditional design, the shield bracket 92 comprises a plurality of contact points 921 in contact respectively with the upper distal edge of each fixing pin 93. The foregoing contact points 921 of the shield bracket 92 are electrically coupled with the upper distal edge 931 of the fixing pin 93 for achieving the effect of grounding and eliminating noises (or known as an electromagnetic interference (EMI) effect).
From the description above, the traditional structural design can achieve the effect of grounding and eliminating noises by contacting the contact point 921 of the shield bracket 92 with the upper distal edge 931 of the fixing pin 93, but the grounding path is limited to two contact points only, and the path for grounding the noises is longer, and thus the electromagnetic interference (EMI) effect is lowered and the life expectancy of the electronic device is affected adversely.